Effectiveness of airway clearance techniques versus control in non-hospitalized infants with moderate acute viral bronchiolitis: A randomized controlled clinical trial

Background  Acute viral bronchiolitis is the most common lower respiratory tract infection in infants < 2-years of age. Airway Clearance Techniques (ACTs) aim to reduce airway obstruction, thereby decreasing airway resistance, improving gas exchange, and reducing respiratory load, all of which can lead to improved clinical stability.

Methods  One hundred ninety-two infants were randomly allocated to one of the following ACTs using flow-based techniques: Assisted Autogenic Drainage (AAD; n = 62), Prolonged Slow Expiration (PSE; n = 63), or a control group (n = 67). The sessions were performed in an outpatient setting, with a duration of 20 min and repeated 48 h later. The outcome measures were the Acute Bronchiolitis Severity Scale (ABSS), Bronchiolitis Score of Sant Joan de Déu (BROSJOD), and peripheral oxygen saturation (SpO₂) recorded immediately after each intervention.

Results  Both airway clearance techniques, PSE and AAD, demonstrated significant improvements in clinical severity scores (ABSS and BROSJOD) and SpO₂ levels compared to the control group, with PSE showing the most pronounced effects. ABSS (ATSboot p = 0.001; η² _p = 0.105) and BROSJOD (ATSboot p = 0.003; η² _p=0.037) significantly differed and interacted with time, decreasing from baseline to 48 h post-treatment. PSE outperformed the controls in reducing ABSS (p < 0.001; Hedges' g = 1.4 vs. g = 0.37). ACTs improved ABSS and BROSJOD scores compared to controls, with PSE showing the greatest SpO₂ increase and wheezing reduction at 20 minutes and one hour post-baseline. At 48 h, the AAD and PSE groups had greater ABSS changes than the controls and fewer retractions at 20 min post-baseline. The AAD group had a lower heart rate, while the controls had higher respiratory rates, and the PSE group had the lowest heart rate. No significant clinical adverse effects were observed.

Conclusions  Both ACTs using flow-based techniques significantly reduced ABSS and BROSJOD scores immediately after treatment and 48 h later in non-hospitalized infants with moderate acute viral bronchiolitis than in the control group. However, PSE intervention showed greater effectiveness in reducing ABSS and increasing SpO₂ than the control and AAD groups.

Keywords
Airway clearance techniques; Chest physiotherapy; Autogenic drainage; Prolonged slow exhalation; Bronchiolitis; Infant; Rehabilitation